Update tools.mk
Fix type of From argument in the listener

Resolves:

riak_api_pb_listener.erl:52: The specified type for the 2nd argument of handle_call/3 (pid()) is not a supertype of {pid(),_}, which is expected type for this argument in the callback of the gen_nb_server behaviour
Fix unmatched list-comprehension value

Resolves:

riak_api_pb_registrar.erl:229: Expression produces a value of type ['true'], but this value is unmatched
Match the return value of ets:new()

Resolves:

riak_api_pb_registration_helper.erl:85: Expression produces a value of type atom() | tid(), but this value is unmatched
Match return value of list-comprehension

Resolves:

riak_api_pb_sup.erl:43: Expression produces a value of type ['ok'], but this value is unmatched
Ignore returns from list-comprehensions and match the folsom registration

Resolves:

riak_api_stat.erl:48: Expression produces a value of type [any()], but this value is unmatched
riak_api_stat.erl:49: Expression produces a value of type ['ok' | {'error',_,'metric_already_exists' | 'nonexistent_metric' | 'unsupported_metric_type'}], but this value is unmatched
riak_api_stat.erl:114: Expression produces a value of type 'ok' | {'error',_,'metric_already_exists' | 'unsupported_metric_type'}, but
Merge pull request #59 from basho/bugfix/sdc/dialyzer

Fix dialyzer warnings

Reviewed-by: cmeiklejohn